Polycrystalline silicon is used in wide applications such as semiconductor elements, LCD (liquid crystal displays), and MEMS (microelectromechanical systems). For example, polycrystalline silicon is used for the gate electrode of MOSFET (metal oxide semiconductor field effect transistor), and a technique for uniformly processing polycrystalline silicon is required to miniaturize the semiconductor elements. Because the surface roughness of the polycrystalline silicon close to the crystal grain size thereof affects the characteristics of semiconductor elements, and decrease the manufacturing yield.